modules/congestion_controller/send_side_congestion_controller_unittest.cc - src - Git at Google

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */

 #include "modules/congestion_controller/include/send_side_congestion_controller.h"
 #include "logging/rtc_event_log/mock/mock_rtc_event_log.h"
 #include "modules/bitrate_controller/include/bitrate_controller.h"
 #include "modules/congestion_controller/include/mock/mock_congestion_observer.h"
 #include "modules/congestion_controller/rtp/congestion_controller_unittests_helper.h"
 #include "modules/pacing/mock/mock_paced_sender.h"
 #include "modules/pacing/packet_router.h"
 #include "modules/remote_bitrate_estimator/include/bwe_defines.h"
 #include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 #include "modules/rtp_rtcp/source/rtcp_packet/transport_feedback.h"
 #include "rtc_base/network/sent_packet.h"
 #include "system_wrappers/include/clock.h"
 #include "test/field_trial.h"
 #include "test/gmock.h"
 #include "test/gtest.h"

 using testing::_;
 using testing::AtLeast;
 using testing::Ge;
 using testing::NiceMock;
 using testing::Return;
 using testing::SaveArg;
 using testing::StrictMock;

 namespace webrtc {

 namespace {
 const webrtc::PacedPacketInfo kPacingInfo0(0, 5, 2000);
 const webrtc::PacedPacketInfo kPacingInfo1(1, 8, 4000);

 const uint32_t kInitialBitrateBps = 60000;

 }  // namespace

 namespace test {

 class LegacySendSideCongestionControllerTest : public ::testing::Test {
  protected:
   LegacySendSideCongestionControllerTest()
       : clock_(123456),
         target_bitrate_observer_(this),
         bandwidth_observer_(nullptr) {}
   ~LegacySendSideCongestionControllerTest() override {}

   void SetUp() override {
     pacer_.reset(new NiceMock<MockPacedSender>());
     controller_.reset(new SendSideCongestionController(
         &clock_, &observer_, &event_log_, pacer_.get()));
     bandwidth_observer_ = controller_->GetBandwidthObserver();

     // Set the initial bitrate estimate and expect the |observer| and |pacer_|
     // to be updated.
     EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
     EXPECT_CALL(*pacer_, SetEstimatedBitrate(kInitialBitrateBps));
     EXPECT_CALL(*pacer_, CreateProbeCluster(kInitialBitrateBps * 3));
     EXPECT_CALL(*pacer_, CreateProbeCluster(kInitialBitrateBps * 5));
     controller_->SetBweBitrates(0, kInitialBitrateBps, 5 * kInitialBitrateBps);
   }

   // Custom setup - use an observer that tracks the target bitrate, without
   // prescribing on which iterations it must change (like a mock would).
   void TargetBitrateTrackingSetup() {
     pacer_.reset(new NiceMock<MockPacedSender>());
     controller_.reset(new SendSideCongestionController(
         &clock_, &target_bitrate_observer_, &event_log_, pacer_.get()));
     controller_->SetBweBitrates(0, kInitialBitrateBps, 5 * kInitialBitrateBps);
   }

   void OnSentPacket(const PacketFeedback& packet_feedback) {
     constexpr uint32_t ssrc = 0;
     controller_->AddPacket(ssrc, packet_feedback.sequence_number,
                            packet_feedback.payload_size,
                            packet_feedback.pacing_info);
     controller_->OnSentPacket(rtc::SentPacket(packet_feedback.sequence_number,
                                               packet_feedback.send_time_ms));
   }

   // Allows us to track the target bitrate, without prescribing the exact
   // iterations when this would hapen, like a mock would.
   class TargetBitrateObserver : public NetworkChangedObserver {
    public:
     explicit TargetBitrateObserver(
         LegacySendSideCongestionControllerTest* owner)
         : owner_(owner) {}
     ~TargetBitrateObserver() override = default;
     void OnNetworkChanged(uint32_t bitrate_bps,
                           uint8_t fraction_loss,  // 0 - 255.
                           int64_t rtt_ms,
                           int64_t probing_interval_ms) override {
       owner_->target_bitrate_bps_ = bitrate_bps;
     }

    private:
     LegacySendSideCongestionControllerTest* owner_;
   };

   void PacketTransmissionAndFeedbackBlock(uint16_t* seq_num,
                                           int64_t runtime_ms,
                                           int64_t delay) {
     int64_t delay_buildup = 0;
     int64_t start_time_ms = clock_.TimeInMilliseconds();
     while (clock_.TimeInMilliseconds() - start_time_ms < runtime_ms) {
       constexpr size_t kPayloadSize = 1000;
       PacketFeedback packet(clock_.TimeInMilliseconds() + delay_buildup,
                             clock_.TimeInMilliseconds(), *seq_num, kPayloadSize,
                             PacedPacketInfo());
       delay_buildup += delay;  // Delay has to increase, or it's just RTT.
       OnSentPacket(packet);
       // Create expected feedback and send into adapter.
       std::unique_ptr<rtcp::TransportFeedback> feedback(
           new rtcp::TransportFeedback());
       feedback->SetBase(packet.sequence_number, packet.arrival_time_ms * 1000);
       EXPECT_TRUE(feedback->AddReceivedPacket(packet.sequence_number,
                                               packet.arrival_time_ms * 1000));
       rtc::Buffer raw_packet = feedback->Build();
       feedback = rtcp::TransportFeedback::ParseFrom(raw_packet.data(),
                                                     raw_packet.size());
       EXPECT_TRUE(feedback.get() != nullptr);
       controller_->OnTransportFeedback(*feedback.get());
       clock_.AdvanceTimeMilliseconds(50);
       controller_->Process();
       ++(*seq_num);
     }
   }

   SimulatedClock clock_;
   StrictMock<MockCongestionObserver> observer_;
   TargetBitrateObserver target_bitrate_observer_;
   NiceMock<MockRtcEventLog> event_log_;
   RtcpBandwidthObserver* bandwidth_observer_;
   PacketRouter packet_router_;
   std::unique_ptr<NiceMock<MockPacedSender>> pacer_;
   std::unique_ptr<SendSideCongestionController> controller_;

   absl::optional<uint32_t> target_bitrate_bps_;
 };

 TEST_F(LegacySendSideCongestionControllerTest, OnNetworkChanged) {
   // Test no change.
   clock_.AdvanceTimeMilliseconds(25);
   controller_->Process();

   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 2, _, _, _));
   EXPECT_CALL(*pacer_, SetEstimatedBitrate(kInitialBitrateBps * 2));
   bandwidth_observer_->OnReceivedEstimatedBitrate(kInitialBitrateBps * 2);
   clock_.AdvanceTimeMilliseconds(25);
   controller_->Process();

   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
   EXPECT_CALL(*pacer_, SetEstimatedBitrate(kInitialBitrateBps));
   bandwidth_observer_->OnReceivedEstimatedBitrate(kInitialBitrateBps);
   clock_.AdvanceTimeMilliseconds(25);
   controller_->Process();
 }

 TEST_F(LegacySendSideCongestionControllerTest, OnSendQueueFull) {
   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
       .WillOnce(Return(PacedSender::kMaxQueueLengthMs + 1));

   EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
   controller_->Process();

   // Let the pacer not be full next time the controller checks.
   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
       .WillOnce(Return(PacedSender::kMaxQueueLengthMs - 1));

   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
   controller_->Process();
 }

 TEST_F(LegacySendSideCongestionControllerTest,
        OnSendQueueFullAndEstimateChange) {
   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
       .WillOnce(Return(PacedSender::kMaxQueueLengthMs + 1));
   EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
   controller_->Process();

   // Receive new estimate but let the queue still be full.
   bandwidth_observer_->OnReceivedEstimatedBitrate(kInitialBitrateBps * 2);
   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
       .WillOnce(Return(PacedSender::kMaxQueueLengthMs + 1));
   //  The send pacer should get the new estimate though.
   EXPECT_CALL(*pacer_, SetEstimatedBitrate(kInitialBitrateBps * 2));
   clock_.AdvanceTimeMilliseconds(25);
   controller_->Process();

   // Let the pacer not be full next time the controller checks.
   // |OnNetworkChanged| should be called with the new estimate.
   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
       .WillOnce(Return(PacedSender::kMaxQueueLengthMs - 1));
   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 2, _, _, _));
   clock_.AdvanceTimeMilliseconds(25);
   controller_->Process();
 }

 TEST_F(LegacySendSideCongestionControllerTest, SignalNetworkState) {
   EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
   controller_->SignalNetworkState(kNetworkDown);

   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
   controller_->SignalNetworkState(kNetworkUp);

   EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
   controller_->SignalNetworkState(kNetworkDown);
 }

 TEST_F(LegacySendSideCongestionControllerTest, OnNetworkRouteChanged) {
   int new_bitrate = 200000;
   testing::Mock::VerifyAndClearExpectations(pacer_.get());
   EXPECT_CALL(observer_, OnNetworkChanged(new_bitrate, _, _, _));
   EXPECT_CALL(*pacer_, SetEstimatedBitrate(new_bitrate));
   rtc::NetworkRoute route;
   route.local_network_id = 1;
   controller_->OnNetworkRouteChanged(route, new_bitrate, -1, -1);

   // If the bitrate is reset to -1, the new starting bitrate will be
   // the minimum default bitrate kMinBitrateBps.
   EXPECT_CALL(
       observer_,
       OnNetworkChanged(congestion_controller::GetMinBitrateBps(), _, _, _));
   EXPECT_CALL(*pacer_,
               SetEstimatedBitrate(congestion_controller::GetMinBitrateBps()));
   route.local_network_id = 2;
   controller_->OnNetworkRouteChanged(route, -1, -1, -1);
 }

 TEST_F(LegacySendSideCongestionControllerTest, OldFeedback) {
   int new_bitrate = 200000;
   testing::Mock::VerifyAndClearExpectations(pacer_.get());
   EXPECT_CALL(observer_, OnNetworkChanged(new_bitrate, _, _, _));
   EXPECT_CALL(*pacer_, SetEstimatedBitrate(new_bitrate));

   // Send a few packets on the first network route.
   std::vector<PacketFeedback> packets;
   packets.push_back(PacketFeedback(0, 0, 0, 1500, kPacingInfo0));
   packets.push_back(PacketFeedback(10, 10, 1, 1500, kPacingInfo0));
   packets.push_back(PacketFeedback(20, 20, 2, 1500, kPacingInfo0));
   packets.push_back(PacketFeedback(30, 30, 3, 1500, kPacingInfo1));
   packets.push_back(PacketFeedback(40, 40, 4, 1500, kPacingInfo1));

   for (const PacketFeedback& packet : packets)
     OnSentPacket(packet);

   // Change route and then insert a number of feedback packets.
   rtc::NetworkRoute route;
   route.local_network_id = 1;
   controller_->OnNetworkRouteChanged(route, new_bitrate, -1, -1);

   for (const PacketFeedback& packet : packets) {
     rtcp::TransportFeedback feedback;
     feedback.SetBase(packet.sequence_number, packet.arrival_time_ms * 1000);

     EXPECT_TRUE(feedback.AddReceivedPacket(packet.sequence_number,
                                            packet.arrival_time_ms * 1000));
     feedback.Build();
     controller_->OnTransportFeedback(feedback);
   }

   // If the bitrate is reset to -1, the new starting bitrate will be
   // the minimum default bitrate kMinBitrateBps.
   EXPECT_CALL(
       observer_,
       OnNetworkChanged(congestion_controller::GetMinBitrateBps(), _, _, _));
   EXPECT_CALL(*pacer_,
               SetEstimatedBitrate(congestion_controller::GetMinBitrateBps()));
   route.local_network_id = 2;
   controller_->OnNetworkRouteChanged(route, -1, -1, -1);
 }

 TEST_F(LegacySendSideCongestionControllerTest,
        SignalNetworkStateAndQueueIsFullAndEstimateChange) {
   // Send queue is full
   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
       .WillRepeatedly(Return(PacedSender::kMaxQueueLengthMs + 1));
   EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
   controller_->Process();

   // Queue is full and network is down. Expect no bitrate change.
   controller_->SignalNetworkState(kNetworkDown);
   controller_->Process();

   // Queue is full but network is up. Expect no bitrate change.
   controller_->SignalNetworkState(kNetworkUp);
   controller_->Process();

   // Receive new estimate but let the queue still be full.
   EXPECT_CALL(*pacer_, SetEstimatedBitrate(kInitialBitrateBps * 2));
   bandwidth_observer_->OnReceivedEstimatedBitrate(kInitialBitrateBps * 2);
   clock_.AdvanceTimeMilliseconds(25);
   controller_->Process();

   // Let the pacer not be full next time the controller checks.
   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
       .WillOnce(Return(PacedSender::kMaxQueueLengthMs - 1));
   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 2, _, _, _));
   controller_->Process();
 }

 TEST_F(LegacySendSideCongestionControllerTest, GetPacerQueuingDelayMs) {
   EXPECT_CALL(observer_, OnNetworkChanged(_, _, _, _)).Times(AtLeast(1));

   const int64_t kQueueTimeMs = 123;
   EXPECT_CALL(*pacer_, QueueInMs()).WillRepeatedly(Return(kQueueTimeMs));
   EXPECT_EQ(kQueueTimeMs, controller_->GetPacerQueuingDelayMs());

   // Expect zero pacer delay when network is down.
   controller_->SignalNetworkState(kNetworkDown);
   EXPECT_EQ(0, controller_->GetPacerQueuingDelayMs());

   // Network is up, pacer delay should be reported.
   controller_->SignalNetworkState(kNetworkUp);
   EXPECT_EQ(kQueueTimeMs, controller_->GetPacerQueuingDelayMs());
 }

 TEST_F(LegacySendSideCongestionControllerTest, GetProbingInterval) {
   clock_.AdvanceTimeMilliseconds(25);
   controller_->Process();

   EXPECT_CALL(observer_, OnNetworkChanged(_, _, _, testing::Ne(0)));
   EXPECT_CALL(*pacer_, SetEstimatedBitrate(_));
   bandwidth_observer_->OnReceivedEstimatedBitrate(kInitialBitrateBps * 2);
   clock_.AdvanceTimeMilliseconds(25);
   controller_->Process();
 }

 TEST_F(LegacySendSideCongestionControllerTest, ProbeOnRouteChange) {
   testing::Mock::VerifyAndClearExpectations(pacer_.get());
   EXPECT_CALL(*pacer_, CreateProbeCluster(kInitialBitrateBps * 6));
   EXPECT_CALL(*pacer_, CreateProbeCluster(kInitialBitrateBps * 12));
   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 2, _, _, _));
   rtc::NetworkRoute route;
   route.local_network_id = 1;
   controller_->OnNetworkRouteChanged(route, 2 * kInitialBitrateBps, 0,
                                      20 * kInitialBitrateBps);
 }

 // Estimated bitrate reduced when the feedbacks arrive with such a long delay,
 // that the send-time-history no longer holds the feedbacked packets.
 TEST_F(LegacySendSideCongestionControllerTest, LongFeedbackDelays) {
   TargetBitrateTrackingSetup();

   const int64_t kFeedbackTimeoutMs = 60001;
   const int kMaxConsecutiveFailedLookups = 5;
   for (int i = 0; i < kMaxConsecutiveFailedLookups; ++i) {
     std::vector<PacketFeedback> packets;
     packets.push_back(
         PacketFeedback(i * 100, 2 * i * 100, 0, 1500, kPacingInfo0));
     packets.push_back(
         PacketFeedback(i * 100 + 10, 2 * i * 100 + 10, 1, 1500, kPacingInfo0));
     packets.push_back(
         PacketFeedback(i * 100 + 20, 2 * i * 100 + 20, 2, 1500, kPacingInfo0));
     packets.push_back(
         PacketFeedback(i * 100 + 30, 2 * i * 100 + 30, 3, 1500, kPacingInfo1));
     packets.push_back(
         PacketFeedback(i * 100 + 40, 2 * i * 100 + 40, 4, 1500, kPacingInfo1));

     for (const PacketFeedback& packet : packets)
       OnSentPacket(packet);

     rtcp::TransportFeedback feedback;
     feedback.SetBase(packets[0].sequence_number,
                      packets[0].arrival_time_ms * 1000);

     for (const PacketFeedback& packet : packets) {
       EXPECT_TRUE(feedback.AddReceivedPacket(packet.sequence_number,
                                              packet.arrival_time_ms * 1000));
     }

     feedback.Build();

     clock_.AdvanceTimeMilliseconds(kFeedbackTimeoutMs);
     PacketFeedback later_packet(kFeedbackTimeoutMs + i * 100 + 40,
                                 kFeedbackTimeoutMs + i * 200 + 40, 5, 1500,
                                 kPacingInfo1);
     OnSentPacket(later_packet);

     controller_->OnTransportFeedback(feedback);

     // Check that packets have timed out.
     for (PacketFeedback& packet : packets) {
       packet.send_time_ms = PacketFeedback::kNoSendTime;
       packet.payload_size = 0;
       packet.pacing_info = PacedPacketInfo();
     }
     ComparePacketFeedbackVectors(packets,
                                  controller_->GetTransportFeedbackVector());
   }

   controller_->Process();

   EXPECT_EQ(kInitialBitrateBps / 2, target_bitrate_bps_);

   // Test with feedback that isn't late enough to time out.
   {
     std::vector<PacketFeedback> packets;
     packets.push_back(PacketFeedback(100, 200, 0, 1500, kPacingInfo0));
     packets.push_back(PacketFeedback(110, 210, 1, 1500, kPacingInfo0));
     packets.push_back(PacketFeedback(120, 220, 2, 1500, kPacingInfo0));
     packets.push_back(PacketFeedback(130, 230, 3, 1500, kPacingInfo1));
     packets.push_back(PacketFeedback(140, 240, 4, 1500, kPacingInfo1));

     for (const PacketFeedback& packet : packets)
       OnSentPacket(packet);

     rtcp::TransportFeedback feedback;
     feedback.SetBase(packets[0].sequence_number,
                      packets[0].arrival_time_ms * 1000);

     for (const PacketFeedback& packet : packets) {
       EXPECT_TRUE(feedback.AddReceivedPacket(packet.sequence_number,
                                              packet.arrival_time_ms * 1000));
     }

     feedback.Build();

     clock_.AdvanceTimeMilliseconds(kFeedbackTimeoutMs - 1);
     PacketFeedback later_packet(kFeedbackTimeoutMs + 140,
                                 kFeedbackTimeoutMs + 240, 5, 1500,
                                 kPacingInfo1);
     OnSentPacket(later_packet);

     controller_->OnTransportFeedback(feedback);
     ComparePacketFeedbackVectors(packets,
                                  controller_->GetTransportFeedbackVector());
   }
 }

 // Bandwidth estimation is updated when feedbacks are received.
 // Feedbacks which show an increasing delay cause the estimation to be reduced.
 TEST_F(LegacySendSideCongestionControllerTest, UpdatesDelayBasedEstimate) {
   TargetBitrateTrackingSetup();

   const int64_t kRunTimeMs = 6000;
   uint16_t seq_num = 0;

   // The test must run and insert packets/feedback long enough that the
   // BWE computes a valid estimate. This is first done in an environment which
   // simulates no bandwidth limitation, and therefore not built-up delay.
   PacketTransmissionAndFeedbackBlock(&seq_num, kRunTimeMs, 0);
   ASSERT_TRUE(target_bitrate_bps_);

   // Repeat, but this time with a building delay, and make sure that the
   // estimation is adjusted downwards.
   uint32_t bitrate_before_delay = *target_bitrate_bps_;
   PacketTransmissionAndFeedbackBlock(&seq_num, kRunTimeMs, 50);
   EXPECT_LT(*target_bitrate_bps_, bitrate_before_delay);
 }

 TEST_F(LegacySendSideCongestionControllerTest, PacerQueueEncodeRatePushback) {
   ScopedFieldTrials pushback_field_trial(
       "WebRTC-PacerPushbackExperiment/Enabled/");
   SetUp();

   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(0));
   controller_->Process();

   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(100));
   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 0.9, _, _, _));
   controller_->Process();

   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(50));
   controller_->Process();

   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(0));
   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
   controller_->Process();

   const uint32_t kMinAdjustedBps = 50000;
   int expected_queue_threshold =
       1000 - kMinAdjustedBps * 1000.0 / kInitialBitrateBps;

   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
       .WillOnce(Return(expected_queue_threshold));
   EXPECT_CALL(observer_, OnNetworkChanged(Ge(kMinAdjustedBps), _, _, _));
   controller_->Process();

   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
       .WillOnce(Return(expected_queue_threshold + 1));
   EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
   controller_->Process();

   EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(0));
   EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
   controller_->Process();
 }

 }  // namespace test
 }  // namespace webrtc
	/*
	* Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
	*
	* Use of this source code is governed by a BSD-style license
	* that can be found in the LICENSE file in the root of the source
	* tree. An additional intellectual property rights grant can be found
	* in the file PATENTS. All contributing project authors may
	* be found in the AUTHORS file in the root of the source tree.
	*/

	#include "modules/congestion_controller/include/send_side_congestion_controller.h"
	#include "logging/rtc_event_log/mock/mock_rtc_event_log.h"
	#include "modules/bitrate_controller/include/bitrate_controller.h"
	#include "modules/congestion_controller/include/mock/mock_congestion_observer.h"
	#include "modules/congestion_controller/rtp/congestion_controller_unittests_helper.h"
	#include "modules/pacing/mock/mock_paced_sender.h"
	#include "modules/pacing/packet_router.h"
	#include "modules/remote_bitrate_estimator/include/bwe_defines.h"
	#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
	#include "modules/rtp_rtcp/source/rtcp_packet/transport_feedback.h"
	#include "rtc_base/network/sent_packet.h"
	#include "system_wrappers/include/clock.h"
	#include "test/field_trial.h"
	#include "test/gmock.h"
	#include "test/gtest.h"

	using testing::_;
	using testing::AtLeast;
	using testing::Ge;
	using testing::NiceMock;
	using testing::Return;
	using testing::SaveArg;
	using testing::StrictMock;

	namespace webrtc {

	namespace {
	const webrtc::PacedPacketInfo kPacingInfo0(0, 5, 2000);
	const webrtc::PacedPacketInfo kPacingInfo1(1, 8, 4000);

	const uint32_t kInitialBitrateBps = 60000;

	} // namespace

	namespace test {

	class LegacySendSideCongestionControllerTest : public ::testing::Test {
	protected:
	LegacySendSideCongestionControllerTest()
	: clock_(123456),
	target_bitrate_observer_(this),
	bandwidth_observer_(nullptr) {}
	~LegacySendSideCongestionControllerTest() override {}

	void SetUp() override {
	pacer_.reset(new NiceMock<MockPacedSender>());
	controller_.reset(new SendSideCongestionController(
	&clock_, &observer_, &event_log_, pacer_.get()));
	bandwidth_observer_ = controller_->GetBandwidthObserver();

	// Set the initial bitrate estimate and expect the \|observer\| and \|pacer_\|
	// to be updated.
	EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
	EXPECT_CALL(*pacer_, SetEstimatedBitrate(kInitialBitrateBps));
	EXPECT_CALL(pacer_, CreateProbeCluster(kInitialBitrateBps 3));
	EXPECT_CALL(pacer_, CreateProbeCluster(kInitialBitrateBps 5));
	controller_->SetBweBitrates(0, kInitialBitrateBps, 5 * kInitialBitrateBps);
	}

	// Custom setup - use an observer that tracks the target bitrate, without
	// prescribing on which iterations it must change (like a mock would).
	void TargetBitrateTrackingSetup() {
	pacer_.reset(new NiceMock<MockPacedSender>());
	controller_.reset(new SendSideCongestionController(
	&clock_, &target_bitrate_observer_, &event_log_, pacer_.get()));
	controller_->SetBweBitrates(0, kInitialBitrateBps, 5 * kInitialBitrateBps);
	}

	void OnSentPacket(const PacketFeedback& packet_feedback) {
	constexpr uint32_t ssrc = 0;
	controller_->AddPacket(ssrc, packet_feedback.sequence_number,
	packet_feedback.payload_size,
	packet_feedback.pacing_info);
	controller_->OnSentPacket(rtc::SentPacket(packet_feedback.sequence_number,
	packet_feedback.send_time_ms));
	}

	// Allows us to track the target bitrate, without prescribing the exact
	// iterations when this would hapen, like a mock would.
	class TargetBitrateObserver : public NetworkChangedObserver {
	public:
	explicit TargetBitrateObserver(
	LegacySendSideCongestionControllerTest* owner)
	: owner_(owner) {}
	~TargetBitrateObserver() override = default;
	void OnNetworkChanged(uint32_t bitrate_bps,
	uint8_t fraction_loss, // 0 - 255.
	int64_t rtt_ms,
	int64_t probing_interval_ms) override {
	owner_->target_bitrate_bps_ = bitrate_bps;
	}

	private:
	LegacySendSideCongestionControllerTest* owner_;
	};

	void PacketTransmissionAndFeedbackBlock(uint16_t* seq_num,
	int64_t runtime_ms,
	int64_t delay) {
	int64_t delay_buildup = 0;
	int64_t start_time_ms = clock_.TimeInMilliseconds();
	while (clock_.TimeInMilliseconds() - start_time_ms < runtime_ms) {
	constexpr size_t kPayloadSize = 1000;
	PacketFeedback packet(clock_.TimeInMilliseconds() + delay_buildup,
	clock_.TimeInMilliseconds(), *seq_num, kPayloadSize,
	PacedPacketInfo());
	delay_buildup += delay; // Delay has to increase, or it's just RTT.
	OnSentPacket(packet);
	// Create expected feedback and send into adapter.
	std::unique_ptr<rtcp::TransportFeedback> feedback(
	new rtcp::TransportFeedback());
	feedback->SetBase(packet.sequence_number, packet.arrival_time_ms * 1000);
	EXPECT_TRUE(feedback->AddReceivedPacket(packet.sequence_number,
	packet.arrival_time_ms * 1000));
	rtc::Buffer raw_packet = feedback->Build();
	feedback = rtcp::TransportFeedback::ParseFrom(raw_packet.data(),
	raw_packet.size());
	EXPECT_TRUE(feedback.get() != nullptr);
	controller_->OnTransportFeedback(*feedback.get());
	clock_.AdvanceTimeMilliseconds(50);
	controller_->Process();
	++(*seq_num);
	}
	}

	SimulatedClock clock_;
	StrictMock<MockCongestionObserver> observer_;
	TargetBitrateObserver target_bitrate_observer_;
	NiceMock<MockRtcEventLog> event_log_;
	RtcpBandwidthObserver* bandwidth_observer_;
	PacketRouter packet_router_;
	std::unique_ptr<NiceMock<MockPacedSender>> pacer_;
	std::unique_ptr<SendSideCongestionController> controller_;

	absl::optional<uint32_t> target_bitrate_bps_;
	};

	TEST_F(LegacySendSideCongestionControllerTest, OnNetworkChanged) {
	// Test no change.
	clock_.AdvanceTimeMilliseconds(25);
	controller_->Process();

	EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 2, _, _, _));
	EXPECT_CALL(pacer_, SetEstimatedBitrate(kInitialBitrateBps 2));
	bandwidth_observer_->OnReceivedEstimatedBitrate(kInitialBitrateBps * 2);
	clock_.AdvanceTimeMilliseconds(25);
	controller_->Process();

	EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
	EXPECT_CALL(*pacer_, SetEstimatedBitrate(kInitialBitrateBps));
	bandwidth_observer_->OnReceivedEstimatedBitrate(kInitialBitrateBps);
	clock_.AdvanceTimeMilliseconds(25);
	controller_->Process();
	}

	TEST_F(LegacySendSideCongestionControllerTest, OnSendQueueFull) {
	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
	.WillOnce(Return(PacedSender::kMaxQueueLengthMs + 1));

	EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
	controller_->Process();

	// Let the pacer not be full next time the controller checks.
	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
	.WillOnce(Return(PacedSender::kMaxQueueLengthMs - 1));

	EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
	controller_->Process();
	}

	TEST_F(LegacySendSideCongestionControllerTest,
	OnSendQueueFullAndEstimateChange) {
	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
	.WillOnce(Return(PacedSender::kMaxQueueLengthMs + 1));
	EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
	controller_->Process();

	// Receive new estimate but let the queue still be full.
	bandwidth_observer_->OnReceivedEstimatedBitrate(kInitialBitrateBps * 2);
	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
	.WillOnce(Return(PacedSender::kMaxQueueLengthMs + 1));
	// The send pacer should get the new estimate though.
	EXPECT_CALL(pacer_, SetEstimatedBitrate(kInitialBitrateBps 2));
	clock_.AdvanceTimeMilliseconds(25);
	controller_->Process();

	// Let the pacer not be full next time the controller checks.
	// \|OnNetworkChanged\| should be called with the new estimate.
	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
	.WillOnce(Return(PacedSender::kMaxQueueLengthMs - 1));
	EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 2, _, _, _));
	clock_.AdvanceTimeMilliseconds(25);
	controller_->Process();
	}

	TEST_F(LegacySendSideCongestionControllerTest, SignalNetworkState) {
	EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
	controller_->SignalNetworkState(kNetworkDown);

	EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
	controller_->SignalNetworkState(kNetworkUp);

	EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
	controller_->SignalNetworkState(kNetworkDown);
	}

	TEST_F(LegacySendSideCongestionControllerTest, OnNetworkRouteChanged) {
	int new_bitrate = 200000;
	testing::Mock::VerifyAndClearExpectations(pacer_.get());
	EXPECT_CALL(observer_, OnNetworkChanged(new_bitrate, _, _, _));
	EXPECT_CALL(*pacer_, SetEstimatedBitrate(new_bitrate));
	rtc::NetworkRoute route;
	route.local_network_id = 1;
	controller_->OnNetworkRouteChanged(route, new_bitrate, -1, -1);

	// If the bitrate is reset to -1, the new starting bitrate will be
	// the minimum default bitrate kMinBitrateBps.
	EXPECT_CALL(
	observer_,
	OnNetworkChanged(congestion_controller::GetMinBitrateBps(), _, _, _));
	EXPECT_CALL(*pacer_,
	SetEstimatedBitrate(congestion_controller::GetMinBitrateBps()));
	route.local_network_id = 2;
	controller_->OnNetworkRouteChanged(route, -1, -1, -1);
	}

	TEST_F(LegacySendSideCongestionControllerTest, OldFeedback) {
	int new_bitrate = 200000;
	testing::Mock::VerifyAndClearExpectations(pacer_.get());
	EXPECT_CALL(observer_, OnNetworkChanged(new_bitrate, _, _, _));
	EXPECT_CALL(*pacer_, SetEstimatedBitrate(new_bitrate));

	// Send a few packets on the first network route.
	std::vector<PacketFeedback> packets;
	packets.push_back(PacketFeedback(0, 0, 0, 1500, kPacingInfo0));
	packets.push_back(PacketFeedback(10, 10, 1, 1500, kPacingInfo0));
	packets.push_back(PacketFeedback(20, 20, 2, 1500, kPacingInfo0));
	packets.push_back(PacketFeedback(30, 30, 3, 1500, kPacingInfo1));
	packets.push_back(PacketFeedback(40, 40, 4, 1500, kPacingInfo1));

	for (const PacketFeedback& packet : packets)
	OnSentPacket(packet);

	// Change route and then insert a number of feedback packets.
	rtc::NetworkRoute route;
	route.local_network_id = 1;
	controller_->OnNetworkRouteChanged(route, new_bitrate, -1, -1);

	for (const PacketFeedback& packet : packets) {
	rtcp::TransportFeedback feedback;
	feedback.SetBase(packet.sequence_number, packet.arrival_time_ms * 1000);

	EXPECT_TRUE(feedback.AddReceivedPacket(packet.sequence_number,
	packet.arrival_time_ms * 1000));
	feedback.Build();
	controller_->OnTransportFeedback(feedback);
	}

	// If the bitrate is reset to -1, the new starting bitrate will be
	// the minimum default bitrate kMinBitrateBps.
	EXPECT_CALL(
	observer_,
	OnNetworkChanged(congestion_controller::GetMinBitrateBps(), _, _, _));
	EXPECT_CALL(*pacer_,
	SetEstimatedBitrate(congestion_controller::GetMinBitrateBps()));
	route.local_network_id = 2;
	controller_->OnNetworkRouteChanged(route, -1, -1, -1);
	}

	TEST_F(LegacySendSideCongestionControllerTest,
	SignalNetworkStateAndQueueIsFullAndEstimateChange) {
	// Send queue is full
	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
	.WillRepeatedly(Return(PacedSender::kMaxQueueLengthMs + 1));
	EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
	controller_->Process();

	// Queue is full and network is down. Expect no bitrate change.
	controller_->SignalNetworkState(kNetworkDown);
	controller_->Process();

	// Queue is full but network is up. Expect no bitrate change.
	controller_->SignalNetworkState(kNetworkUp);
	controller_->Process();

	// Receive new estimate but let the queue still be full.
	EXPECT_CALL(pacer_, SetEstimatedBitrate(kInitialBitrateBps 2));
	bandwidth_observer_->OnReceivedEstimatedBitrate(kInitialBitrateBps * 2);
	clock_.AdvanceTimeMilliseconds(25);
	controller_->Process();

	// Let the pacer not be full next time the controller checks.
	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
	.WillOnce(Return(PacedSender::kMaxQueueLengthMs - 1));
	EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 2, _, _, _));
	controller_->Process();
	}

	TEST_F(LegacySendSideCongestionControllerTest, GetPacerQueuingDelayMs) {
	EXPECT_CALL(observer_, OnNetworkChanged(_, _, _, _)).Times(AtLeast(1));

	const int64_t kQueueTimeMs = 123;
	EXPECT_CALL(*pacer_, QueueInMs()).WillRepeatedly(Return(kQueueTimeMs));
	EXPECT_EQ(kQueueTimeMs, controller_->GetPacerQueuingDelayMs());

	// Expect zero pacer delay when network is down.
	controller_->SignalNetworkState(kNetworkDown);
	EXPECT_EQ(0, controller_->GetPacerQueuingDelayMs());

	// Network is up, pacer delay should be reported.
	controller_->SignalNetworkState(kNetworkUp);
	EXPECT_EQ(kQueueTimeMs, controller_->GetPacerQueuingDelayMs());
	}

	TEST_F(LegacySendSideCongestionControllerTest, GetProbingInterval) {
	clock_.AdvanceTimeMilliseconds(25);
	controller_->Process();

	EXPECT_CALL(observer_, OnNetworkChanged(_, _, _, testing::Ne(0)));
	EXPECT_CALL(*pacer_, SetEstimatedBitrate(_));
	bandwidth_observer_->OnReceivedEstimatedBitrate(kInitialBitrateBps * 2);
	clock_.AdvanceTimeMilliseconds(25);
	controller_->Process();
	}

	TEST_F(LegacySendSideCongestionControllerTest, ProbeOnRouteChange) {
	testing::Mock::VerifyAndClearExpectations(pacer_.get());
	EXPECT_CALL(pacer_, CreateProbeCluster(kInitialBitrateBps 6));
	EXPECT_CALL(pacer_, CreateProbeCluster(kInitialBitrateBps 12));
	EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 2, _, _, _));
	rtc::NetworkRoute route;
	route.local_network_id = 1;
	controller_->OnNetworkRouteChanged(route, 2 * kInitialBitrateBps, 0,
	20 * kInitialBitrateBps);
	}

	// Estimated bitrate reduced when the feedbacks arrive with such a long delay,
	// that the send-time-history no longer holds the feedbacked packets.
	TEST_F(LegacySendSideCongestionControllerTest, LongFeedbackDelays) {
	TargetBitrateTrackingSetup();

	const int64_t kFeedbackTimeoutMs = 60001;
	const int kMaxConsecutiveFailedLookups = 5;
	for (int i = 0; i < kMaxConsecutiveFailedLookups; ++i) {
	std::vector<PacketFeedback> packets;
	packets.push_back(
	PacketFeedback(i * 100, 2 * i * 100, 0, 1500, kPacingInfo0));
	packets.push_back(
	PacketFeedback(i * 100 + 10, 2 * i * 100 + 10, 1, 1500, kPacingInfo0));
	packets.push_back(
	PacketFeedback(i * 100 + 20, 2 * i * 100 + 20, 2, 1500, kPacingInfo0));
	packets.push_back(
	PacketFeedback(i * 100 + 30, 2 * i * 100 + 30, 3, 1500, kPacingInfo1));
	packets.push_back(
	PacketFeedback(i * 100 + 40, 2 * i * 100 + 40, 4, 1500, kPacingInfo1));

	for (const PacketFeedback& packet : packets)
	OnSentPacket(packet);

	rtcp::TransportFeedback feedback;
	feedback.SetBase(packets[0].sequence_number,
	packets[0].arrival_time_ms * 1000);

	for (const PacketFeedback& packet : packets) {
	EXPECT_TRUE(feedback.AddReceivedPacket(packet.sequence_number,
	packet.arrival_time_ms * 1000));
	}

	feedback.Build();

	clock_.AdvanceTimeMilliseconds(kFeedbackTimeoutMs);
	PacketFeedback later_packet(kFeedbackTimeoutMs + i * 100 + 40,
	kFeedbackTimeoutMs + i * 200 + 40, 5, 1500,
	kPacingInfo1);
	OnSentPacket(later_packet);

	controller_->OnTransportFeedback(feedback);

	// Check that packets have timed out.
	for (PacketFeedback& packet : packets) {
	packet.send_time_ms = PacketFeedback::kNoSendTime;
	packet.payload_size = 0;
	packet.pacing_info = PacedPacketInfo();
	}
	ComparePacketFeedbackVectors(packets,
	controller_->GetTransportFeedbackVector());
	}

	controller_->Process();

	EXPECT_EQ(kInitialBitrateBps / 2, target_bitrate_bps_);

	// Test with feedback that isn't late enough to time out.
	{
	std::vector<PacketFeedback> packets;
	packets.push_back(PacketFeedback(100, 200, 0, 1500, kPacingInfo0));
	packets.push_back(PacketFeedback(110, 210, 1, 1500, kPacingInfo0));
	packets.push_back(PacketFeedback(120, 220, 2, 1500, kPacingInfo0));
	packets.push_back(PacketFeedback(130, 230, 3, 1500, kPacingInfo1));
	packets.push_back(PacketFeedback(140, 240, 4, 1500, kPacingInfo1));

	for (const PacketFeedback& packet : packets)
	OnSentPacket(packet);

	rtcp::TransportFeedback feedback;
	feedback.SetBase(packets[0].sequence_number,
	packets[0].arrival_time_ms * 1000);

	for (const PacketFeedback& packet : packets) {
	EXPECT_TRUE(feedback.AddReceivedPacket(packet.sequence_number,
	packet.arrival_time_ms * 1000));
	}

	feedback.Build();

	clock_.AdvanceTimeMilliseconds(kFeedbackTimeoutMs - 1);
	PacketFeedback later_packet(kFeedbackTimeoutMs + 140,
	kFeedbackTimeoutMs + 240, 5, 1500,
	kPacingInfo1);
	OnSentPacket(later_packet);

	controller_->OnTransportFeedback(feedback);
	ComparePacketFeedbackVectors(packets,
	controller_->GetTransportFeedbackVector());
	}
	}

	// Bandwidth estimation is updated when feedbacks are received.
	// Feedbacks which show an increasing delay cause the estimation to be reduced.
	TEST_F(LegacySendSideCongestionControllerTest, UpdatesDelayBasedEstimate) {
	TargetBitrateTrackingSetup();

	const int64_t kRunTimeMs = 6000;
	uint16_t seq_num = 0;

	// The test must run and insert packets/feedback long enough that the
	// BWE computes a valid estimate. This is first done in an environment which
	// simulates no bandwidth limitation, and therefore not built-up delay.
	PacketTransmissionAndFeedbackBlock(&seq_num, kRunTimeMs, 0);
	ASSERT_TRUE(target_bitrate_bps_);

	// Repeat, but this time with a building delay, and make sure that the
	// estimation is adjusted downwards.
	uint32_t bitrate_before_delay = *target_bitrate_bps_;
	PacketTransmissionAndFeedbackBlock(&seq_num, kRunTimeMs, 50);
	EXPECT_LT(*target_bitrate_bps_, bitrate_before_delay);
	}

	TEST_F(LegacySendSideCongestionControllerTest, PacerQueueEncodeRatePushback) {
	ScopedFieldTrials pushback_field_trial(
	"WebRTC-PacerPushbackExperiment/Enabled/");
	SetUp();

	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(0));
	controller_->Process();

	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(100));
	EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 0.9, _, _, _));
	controller_->Process();

	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(50));
	controller_->Process();

	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(0));
	EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
	controller_->Process();

	const uint32_t kMinAdjustedBps = 50000;
	int expected_queue_threshold =
	1000 - kMinAdjustedBps * 1000.0 / kInitialBitrateBps;

	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
	.WillOnce(Return(expected_queue_threshold));
	EXPECT_CALL(observer_, OnNetworkChanged(Ge(kMinAdjustedBps), _, _, _));
	controller_->Process();

	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
	.WillOnce(Return(expected_queue_threshold + 1));
	EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
	controller_->Process();

	EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(0));
	EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
	controller_->Process();
	}

	} // namespace test
	} // namespace webrtc